This is an innovative proposal to determine the capacity of molecular analysis of exhaled breath condensate filters (EBCF) to predict ventilator associated pneumonia (VAP) in trauma intensive care unit patients. Based upon preliminary data of 51 patients suspected of having VAP, who underwent bronchoalveolar lavage, we have previously demonstrated a strong correlation between bronchoalveolar lavage and breath condensate quantitative PCR. The goal of this proposal is to understand the changes that occur in the pulmonary microbial community of mechanically ventilated, critically injured adults to support the development of molecular analysis of EBCF to provide an earlier, more sensitive and specific diagnosis of VAP, to enable: 1) earlier recognition of a developing pneumonia, 2) targeted antimicrobial therapy, and 3) assessment of treatment response.